Formic acid esters



Patented Aug. 20, 1946 UNITED STATES PATENT OFFICE.

Edward P. Bartlett, Wilmington, Del., assignor to- E. I'. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Original application November 24,- 1939, Serial No. 305,929. Divided andthis-applica'tion December 9, 1943, Serial'No. 513,639

Claims. 1

This invention relates-to a process for the preparation of formic acid esters and to the products of that process; It more particularly relates to the preparation of polyhydric alcohol polyformates by the interaction of polyhydri alcohols with carbon monoxide and tothe product of such reactions. This application'is a division of application Ser. No, 305,929 filed November 24, 1939.

An object of the present invention is to provide an-improved process for the preparation of formic acid esters. Another object of the invention is toprovide a process for the preparation of formates by the interaction of polyhydric alcohols, monoalkyl ethers of polyhydric alcohols or monoalkyloxy ethers of polyhydric alcohols with carbon monoxide. A further object of the invention is to provide a process for the preparation of glycol diformate by the interaction of ethylene glycol with carbon monoxide in the presence of an alkali metal glycolate or other alkoxide catalyst. Still another object involves the preparation of polyformic acid esters of the polyhydric alcohols by interacting the latter with carbon monoxide under suitable temperature and pressure conditions in the presence of their respective alkali metal alcoholates or other alkali metal alkoxide catalyst. Other obj ects and advantages of the invention will hereinafter appear.

The process may be described as involving the following steps of dissolving in the polyhydric alcohol or ether derivative thereof an alkaline catalyst such as an alkali or an alkaline earth metal, or mixing a suitable alkaline catalyst such as an alkali metal or alkaline earth metal alkoxide, with a polyhydric alcohol or ether derivative thereof, contacting the resulting mixture with carbon monoxide in a suitable reaction Vessel, raising the temperature until the reaction starts and when thereaction is substantially complete separating the formate from the reaction mixture.

The polyhydric alcohols which may be reacted in accord with the invention include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, and the higher analogous and homologous polyhydric alcohols, as well as glycerol and the like. Derivatives of thepolyhydric alcohols in which the OH, or the H of the OH, is substituted may also be used, providing there is present a free hydroxyl group in the molecule. Such derivatives include the monoalkyl ethers of ethylene glycol and the above-designated glycols, e. g., monomethyl, ethyl, propyl and higher ethers of ethylene glycol, the monoaryl ethers of ethylene glycol, such as monobenzyl and monotolyl ethers of'the alcohol, and the monoalkoxyalkyl ethers of ethyleneglycol, such as may be designatedby the formula, ROCH2O(-CH2) 20H, which; generically, represents such alcohols as (methoxy methox-y) ethanol, CHiOCHiO (CH2) 20H; (ethoxymethoxy) ethanol, C2H5OCH2O CH2 20H (propoxy methox-y)ethan0l, CaHqOCI-I2O(CH2) 20H; (butoxy methoxy) ethanol, C3H9OCH2O (CH2) 20H; (methoxy isopropoxy) ethanol,

CHsOC (CH3) 2O (CH2) 20H (methcxy ethoxy'methoxy) ethanol,

CHsO (CH2) 2O' CH2O (CH2) 2OH (alpha-methoxy ethoxy) ethanol,

CH3OCH(CH3) 0 (CH2) 201-1 a d (alpha-ethoxy ethoxy) ethanol,

cznsocmcne 04cm) 20H and similarly, higher substituted alcohols areineluded such, for example, as (methoxy methoxy) propanol, CHaOCI-IzOiCHzhOI-l; beta-(methoxy methoxy) propanol, CHsOCHzOCI-HCI-Ia) CH'zOH; (methoxy methoxy) butanol,

CHsOCI-IzO (CH2) 40H and the higher corresponding alcoholsas well as.

their homologues. Other specific examples which may likewise be included are the mono-(methoxy methyl) ether of diethylene glycol,

CI-I3OCH2O (CH2) 2O (CI-I2) 20H as well as the. corresponding (ethoxy methyl); (propoxy methyl), (butoxy methyl), (methoxy ethoxy methyl) ethers of diethylene glycol, as Well as tri-ethylene glycol. These. alcohols are prepared in accord with the process described in the CH2OH(CH20)n(CI-I2) 20H, in which n is one '01" more.

The polyhydric alcohol acid monoesters may likewise be converted to the corresponding for--- mates. Examples of this class of compounds are the ethylene glycol monoalkyl esters, such as ethylene glycol monomethyl acetate, ethylene gly-r col monoethyl acetate, ethylene glycol monomethyl propionate, diethylene glycol monoethyl ether acetate, and the like.

In addition to the. above polyhydricalcohols in which the OH group or the hydrogen of the OH group is substituted by organic groups, there may I be reacted, in accord with my invention, polyately elevated temperature, but the reaction proceeds also at ordinary temperatures with suflicient speed, if the carbon monoxide is brought into intimate contact with the liquid. The-temperature may range from in the order of 50 to 250 C. with the preferred temperature between approximately 60 and 150 C. The reaction, as has been indicated, is conducted preferablya-t superatmospheric pressures usually in the neighborhood of 10 to 700 atmospheres, although the reaction will proceed down to in the proximity of atmospheric pressures and also at pressures above 700 atmospheres.

In addition to the alkali and alkaline earth metal alkoxide catalysts disclosed, other alkaline catalysts may be used, such as the formates of the same metals. Such catalysts as, for example, sodium formate usually require a somewhat higher temperature to be as effective as the alkoxide-type catalysts, i. e., temperatures of 100 C. or above.

The carbon monoxide used in this reaction may be derived from any suitable source and is preferably substantially pure and particularly free from gases which will contaminate theester produced or form undesirable products. There may be'present with the carbon monoxide, however,

diluent gases which do not enter into the reaction such, for example, as nitrogen, hydrogen, or methane and similar inert diluents.

Examples will now be given illustrating preferred embodiments of the invention, which is not restricted to the particular details therein given. The parts are by weight unless otherwise indicated.

Example 1.An autoclave was charged with a mixture of 3542 parts containing approximately 3495 parts of ethylene glycol, in which was dissolved 47 parts of metallic sodium. CalbOnll'lO-noxide was introduced into the closed autoclave and thepressure therein increased by the introduction of carbon monoxide until a pressure between 200 and 400 atmospheres was obtained. The temperature was'raised to between 70 and 100 C. and held within approximately that range for 5% hours. Ethylene glycol diformate was obtained.

Example 2.-An autoclave was charged with 3321 parts of a mixture containing 3285 parts of propylene glycol (propanediol-1:2), in which had been dissolved 36 parts of metallic sodium. Carbon monoxide was introduced and the pressure raised thereby to between 200 and 400 atmospheres. The temperature was raised to between 70 and 100 C. and the reaction held between these temperature limits for approximately 5 4 hours. The product was distilled and the distillate was found to contain:

Per cent Formic acid 1.8 Water 0.7 Propylene glycol 19.3 Propylene glycol monof0rmate 41.9 Propylene glycol diformate 36.3

Propylene diformate has a boiling point of 116 C. at 101 mm., a refractive index to the sodium lime of 1.4130 at 23 C. and a density of 1.136 at .25 C; It is water-white, odorless. and soluble in all proportions in alcohol and ether and to the extent of 8.6 grams in cc. of water at room temperature.

Example 3.The reaction illustrated by Example 1 was repeated using 3575 parts of a mixture containing 3481 parts of ethylene glycol, in which had been dissolved 94 parts of sodium metal. The same pressure, temperature and. time of reaction specified in Example 1 were used. However, because of the higher concentration of catalyst, reaction rate was greater and the product richer in ester. The products from the two syntheses were combined and distilled. Analysis of the distillate showed:

The polyhydric alcohol formates of this invention are particularly useful as solvents for extracting purposes, as solvents in cellulose ester and ether lacquers and the like and especially for use as intermediates in organic synthesis. From a. consideration of the above specification, it. will be appreciated that many changes may be made therein without departing from the scope of the invention or sacrificing any of the advantages that may be derived therefrom.

Iclaim:

1. A process for the preparation of ethylene glycol diformate which comprises reacting ethylene glycol with a carbon monoxide in the presence of an alkali metal alkoxide catalyst at a pressure between 200 and 700 atmospheres and at a temperature between 50 and 250 C.

2. A process for the preparation of 1,2-propylene glycol diformate which comprises'reacting 1,2-propylene glycol with carbon monoxide in the presence of an alkali metal alkoxide catalyst at a pressure between 200 and 700 atmospheres and at a temperature betewen 50 and 250 C.

3. A process for the preparation of ethylene glycol diformate which comprises contacting carbon monoxide and ethylene glycol with sodium methoxide at a pressure between 10 and 700 atmospheres and a temperature between 50 and 250 C.

4. A process for the preparation of 1,2-propylene glycol diformate which comprises contacting carbon monoxide and 1,2-propylene glycol with sodium methoxide at a. pressure between 10 and 700 atmospheres and a temperature between 50 and 250 C.

5. A process for the preparation of vicinal glycol diformate which comprises heating carbon monoxide and a. liquid vicinal glycol with a metal alkoxide catalyst at a pressure above atmospheric.

EDWARD P. BARTLETT.- Q 

